A storage device such as a flash memory module stores encoded data. The encoded data is expected to be decoded by a memory controller. The memory controller is expected to successfully decode the encoded data during the lifespan of the flash memory module. A failure of the memory controller to decode encoded data, for example, when the amount of errors in a memory are beyond the ability of the controller to correct, renders the encoded data invalid, and the controller responds to a retrieval request with an error message. Such a failure may occur, for example, when the flash memory is exposed to high temperatures, or for other reasons.
Memory controllers are expected to be relatively cheap and are required to read and decode encoded information in real time. Accordingly, these requirements may impose a low sampling rate of the encoded data and a use of a decoding scheme that has limited error correction capabilities. Typically, memory controllers use “hard” decoding techniques, i.e., provide a definite determination of the data stored on each cell. However, such techniques may be insufficient to retrieve damaged data.